How do I set the 'expire' option?

The code generally looks good, and I have tested this in simplytest.me with https://git.drupalcode.org/project/securitytxt/-/merge_requests/5.patch and confirmed that it works as expected:

1. I navigated to admin /config/system/securitytxt
2. I added dummy input for the email and phone fields, since at least one contact method needs to be provided
3. scrolled down and found the "Expires" fieldset
4. the "Expire date" field, was marked as required 👍 (since the RFC states that this is a requirement)
5. the date was set to a year in the future 👍
6. saved configuration
7. I navigated to /admin/config/development/configuration/single/export and confirmed that the settings were saved
8. the expiration date was saved as a Unix timestamp 👍
9. I then navigated to /.well-known/security.txt and the output as as expected (mostly):
   

   Contact: security@example.com
   Contact: 123456789
   Expires: 2024-01-27T02:37:37+00:00
   Signature: https://master-k6xfydjaryuxcpxtpgvolwenkzysbfpd.tugboatqa.com/.well-known/security.txt.sig
   

I'm marking this as "Needs Work", since the standard requires this to be in ISO 8601.

...I've added a comment with a simple code suggestion to fix the date output according to the RFC expectation, but as I mentioned in my earlier comment, perhaps we should offer an option to be outputting the date in UTC instead of local time.

What adding a requirements check that alerts/warns if the expiration date is (about to) arrive? That could be monitored as well then.

I like @Berdir's suggestion to add logging and/or messages/alerts that it's going to expire soon... not sure that should be configurable but, if it is, it should default to being enabled which would require an update hook to enable it upon database update.

According to the PHP docs DateTime::ATOM is ISO 8601 compliant where DateTime::ISO8601 isn't, see
https://www.php.net/manual/en/class.datetimeinterface.php#datetimeinterf...

DATE_ISO8601
ISO-8601 (example: 2005-08-15T15:52:01+0000)
Note: This format is not compatible with ISO-8601, but is left this way for backward compatibility reasons. Use DateTimeInterface::ISO8601_EXPANDED, DateTimeInterface::ATOM for compatibility with ISO-8601 instead. (ref ISO8601:2004 section 4.3.3 clause d)

So, the current date format in the patch seems to be correct. I think adding #8 sounds great, but could be a follow up issue, since according to https://securitytxt.org/ 'Expires' is now required I don't think we should block this on adding more features.

Oops, bit to quick, this needs to update the config schema in config/schema/securitytxt.schema.yml

Added new setting to schema

Added patch to be used together with 3371000. Just for convenience.

Test Lendude's adjustments and in MR#5 works.

Thank you! Committed! 🥂

Automatically closed - issue fixed for 2 weeks with no activity.